1. Field of the Invention
The present invention provides an inexpensive device for preventing the loosening of coupling nuts on fluid lines.
2. Description of the Prior Art
Fittings for providing a leak-proof attachment between a hydraulic or other fluid conducting tube and associated hardware such as actuators, manifolds, etc. are well known. Examples of such fittings are disclosed in U.S. Pat. No. 3,702,707 to Rosan, Sr.
Various techniques have been proposed to fix the torquing coupling nut, or B-nut, relative to the fitting so that the B-nut does not back off the fitting. For example, a lockwire, passed through holes formed in the B-nut and secured to a boss on the parent material, is used in the '707 patent fittings to accomplish this result.
In co-pending application Ser. No. 430,317, filed Oct. 31, 1989 and assigned to the assignee of this application, other techniques for fixing the B-nut relative to the fitting are disclosed. In particular, a separate sleeve having a shape conforming to the outer configuration of the B-nut slides over the B-nut down to the parent material so that the sleeve engages both the B-nut and the lockring embedded in the parent material.
The disadvantage of using a lockwire to fix the B-nut relative to the fitting is that it is cumbersome and requires drilling a hole in one or more corners of the B-nut and finding a boss or tie-down location on the parent material to keep the B-nut from backing off. The lockwire is not a positive mechanical locking device and installation of lockwires may be subject to inconsistent techniques. The sleeve, and the various modifications thereto, disclosed in the co-pending application require retrofitting to existing systems to be fully effective, such as modifications to the B-nut.
Four patents developed during a patentability search, U.S. Pat. Nos. 3,329,190, 4,708,555 and 5,090,855 and German Patent 2413760 all relate to lockwashers and are designed to prevent the loss of locking torque in a conventional nut and bolt clamp-up. U.S. Pat. No. 1,066,761, also developed during the search, utilizes a modified coil spring and two special clutches and requires a special tool to disengage the coil spring from the clutch. These devices are not designed for coupling components in fluid currents.
U.S. Pat. No. 5,058,930 to Schlosser discloses a high pressure coupling and utilizes a cylindrical arrangement of spaced fingers on a thin wall cylinder having protruding tips directed radially inward, the tips being accommodated in associated annular grooves to prevent disconnection of the coupling component from the associated fluid circuit. Although this coupling component is designed to prevent disconnection as noted above, the complexity thereof, the resultant higher costs and the lack of a retrofit capability makes alternate designs more desirable.
What is desired therefore, is to provide an inexpensive device for preventing the loosening of coupling nuts on air or hydraulic lines from the fitting and which can easily be retrofit to existing installations.